38 lines
No EOL
1.1 KiB
TypeScript
38 lines
No EOL
1.1 KiB
TypeScript
// A type guard of the form x instanceof C, where C is of a subtype of the global type 'Function'
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// and C has a property named 'prototype'
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// - when true, narrows the type of x to the type of the 'prototype' property in C provided
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// it is a subtype of the type of x, or
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// - when false, has no effect on the type of x.
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interface C1 {
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(): C1;
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prototype: C1;
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p1: string;
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}
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interface C2 {
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(): C2;
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prototype: C2;
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p2: number;
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}
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interface D1 extends C1 {
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prototype: D1;
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p3: number;
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}
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var str: string;
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var num: number;
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var strOrNum: string | number;
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var c1: C1;
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var c2: C2;
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var d1: D1;
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var c1Orc2: C1 | C2;
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str = c1Orc2 instanceof c1 && c1Orc2.p1; // C1
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num = c1Orc2 instanceof c2 && c1Orc2.p2; // C2
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str = c1Orc2 instanceof d1 && c1Orc2.p1; // C1
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num = c1Orc2 instanceof d1 && c1Orc2.p3; // D1
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var c2Ord1: C2 | D1;
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num = c2Ord1 instanceof c2 && c2Ord1.p2; // C2
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num = c2Ord1 instanceof d1 && c2Ord1.p3; // D1
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str = c2Ord1 instanceof d1 && c2Ord1.p1; // D1
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var r2: D1 | C2 = c2Ord1 instanceof c1 && c2Ord1; // C2 | D1
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